/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.config;

import org.springframework.aop.aspectj.AspectInstanceFactory;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.Ordered;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * Implementation of {@link AspectInstanceFactory} that locates the aspect from the
 * {@link org.springframework.beans.factory.BeanFactory} using a configured bean name.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 */
public class SimpleBeanFactoryAwareAspectInstanceFactory implements AspectInstanceFactory, BeanFactoryAware {

    @Nullable
    private String aspectBeanName;

    @Nullable
    private BeanFactory beanFactory;


    /**
     * Set the name of the aspect bean. This is the bean that is returned when calling
     * {@link #getAspectInstance()}.
     */
    public void setAspectBeanName(String aspectBeanName) {
        this.aspectBeanName = aspectBeanName;
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
        Assert.notNull(this.aspectBeanName, "'aspectBeanName' is required");
    }


    /**
     * Look up the aspect bean from the {@link BeanFactory} and returns it.
     *
     * @see #setAspectBeanName
     */
    @Override
    public Object getAspectInstance() {
        Assert.state(this.beanFactory != null, "No BeanFactory set");
        Assert.state(this.aspectBeanName != null, "No 'aspectBeanName' set");
        return this.beanFactory.getBean(this.aspectBeanName);
    }

    @Override
    @Nullable
    public ClassLoader getAspectClassLoader() {
        if (this.beanFactory instanceof ConfigurableBeanFactory) {
            return ((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader();
        } else {
            return ClassUtils.getDefaultClassLoader();
        }
    }

    @Override
    public int getOrder() {
        if (this.beanFactory != null && this.aspectBeanName != null &&
                this.beanFactory.isSingleton(this.aspectBeanName) &&
                this.beanFactory.isTypeMatch(this.aspectBeanName, Ordered.class)) {
            return ((Ordered) this.beanFactory.getBean(this.aspectBeanName)).getOrder();
        }
        return Ordered.LOWEST_PRECEDENCE;
    }

}
